Method of setting wool textiles



United States Patent 3,216,781 METHOD OF SETTING WOOL TEXTILES Clay E. Par-do, Jr., Albany, and Robert E. Foster, Concord, Califi, assignors to the United States of America as represented by the Secretary of Agriculture No Drawing. Filed Jan. 18, 1962, Ser. No. 167,196

1 Claim. ((11. 8127.6) (Granted under Title 35, US. Code (1952), see. 266) A non-exclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the United States Government, with the power to grant subliccnses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to and has as its primary object the provision of novel methods for imparting to wool textiles durable creases, folds, pleats, or other structural arrangements as may be selected by the operator. Further objects of the invention will be obvious from the following description wherein parts and percentages are by weight unless otherwise specified.

' a It is, of course, well known that garments of all types are provided with some sort of fabric arrangement, for example, pleats, creases, etc. Such deformations are conventionally produced by ironingthe garment while constrained in the desired pattern. However, these arrangements are but temporary and when the garment is subjected to wear or is exposed to humid conditions the creases, pleats, etc. disappear leaving the garment in a shapeless condition. Materials such as starch are widely employed to obtain more durable creases. However, impregnation of the textile with starch and similar materials has the drawback that the textile is rendered stiff and harsh so that it does not have the original characteristics of the untreated fabric.

The process of the invention affords many advantages not realized by prior techniques. Some of these advantages are explained below.

In the first place, the deformations produced by application of the invention are durable, that is, they are essentially permanent in practical consideration. The treated textiles may be subjected to soaking in cold or even hot water without loss of the deformed structure. Garments treated in accordance with the invention may be worn in the rain or subjected to other humid conditions without loss of pleats, creases, etc. The treated textiles may even be subjected to washing in conventional aqueous soap or detergent formulations with little detriment to the creases, pleats, or other arrangements as may be present.

A most significant advantage of the process of the invention is that the durable arrangements are accomplished Without impairing the desirable properties of the textile. That is to say, such properties as color, hand, elasticity, porosity, resilience, strength, wear-resistance, etc., are not harmed. For example, textiles treated in accordance with the invention exhibit essentially the same hand as the original fabric. This is in utter contrast to prior processes which depend for their effectiveness on the application of shellac, gums, starches, resins, or other highmolecular weight coating materials. In those cases there is a substantial stiffening of the material so that the original hand of the fabric is impaired. The process of the invention does not involve constraining the shape of the textiles by a stiffening of the fabric but primarily by a chemical rearrangement of the structure of the fibers into a new structural pattern.

Another advantage of the invention is that the treatment confers a fiat-setting effect on the fabric. Ordinarily, when wool fabrics are immersed in water and subsequently air-dried, their surface has a mussy appearance due to fibers raising from the yarn during Water wetting and then protruding from the fabric surface after drying. In contrast, fabrics treated in accordance with the invention do not display this mussiness after wetting and drying but retain a smooth, pressed appearance.

A further advantage of the process of the invention is that the products do not have any objectionable odor, even when moistened. This is in sharp contrast to many previous setting treatments which involve the use of compounds which impart disagreeable odors to the treated wool, these odors being especially intense when the products are moistened.

In applying the process of the invention, the compound N,N'-methylene bis-acrylamide (hereinafter referred to as MBA) is distributed on the textile, the textile is arranged in the desired pattern and then while constraining it in such pattern heat is applied to set the arrangement.

The MBA is usually applied to the textile dissolved in a volatile, inert solvent, for example, methanol, ethanol, acetone, water, etc., water being preferred as the most convenient and economical solvent. The concentration of MBA in the solution is not critical and may be varied. When MBA is applied in aqueous solution, the concentration thereof is usually about from 0.2% up to about 3%, the latter representing a saturated solution at 25 C.

The MBA solution is applied to the textile by any conventional technique, for example, immersion, brushing, or spraying. Usually, it is preferred to apply the solution by spraying. For example, in treating trousers in accordance with the invention, the MBA solution is sprayed along the length of the legs of the garment Where the creases will be formed.

The amount of MBA applied to the textile is not critical. Thus, MBA exhibits a very potent effect in enabling the formation of durable pleats and any amount thereof applied to the textile will result in significant improvement over conventional creasing, pleating, or other type of fiber deformation produced by pressing with a hot iron or similar device. Usually, it is preferred that the total amount of MBA applied to the textile be not over 5% to avoid changing the hand of the textile.

After applying MBA to the textile, the textile is deformed to the desired pattern. The deformation may involve such manipulations as folding over sections of the textile, creasing, pleating, or shaping on suitable mandrels or dies. For example, in applying the process to garments, these articles are arranged on a flat surface with the desired areas folded over, creased, or otherwise arranged as conventional in arranging garments for pressing. Where more complex configurations are involved the textile may be compressed between dies having the desired shape. For example, ribbed efiects may be obtained by constraining the fabric between dies having corrugated surfaces; pleated effects may be obtained by constraining the fabric between dies having mating V-shaped projections. Yarns may be crimped by compressing between corrugated surfaces. Further extensions of these principles will be obvious to those versed in the textile art.

In any event, the textile is constrained in the deformed position while heat is applied to it to set the deformation. The heat treatment, or curing as it may be termed, is generally' accomplished by contacting the textile with steam or with heated platens, rollers, dies, or the like. Also, the textile may be placed in an oven or subjected to radiation from infra-red heaters or the like. For this establishment of pleats, creases, and the like, a conventional tailors steam-press is quite satisfactory as the textile can be subjected to direct contact with steam while held in position in the deformed state by the press platens. Generally, the heating, whether by steam or a hot roller,

die, platen, etc., is at about 85 to 150 C. The time for cure is decreased with increasing temperature. Depending on the temperature, the time for cure will be on the order of 0.5 to 15 minutes. In any particular case, pilot trials may be conducted with different heating times and testing the durability of the deformations in the treated textile by soaking them in water and observing their appearance. From such trials it is simple to determine the proper time of heating for the main batch of textile to be treated. Generally, it is preferred to heat the MBA- treated textile at a temperature of about from 140 to 150 C., in which case the deformation is set in about 0.5 to 5 minutes. Also, heating by direct contact with steam is generally preferred as the penetration of the steam into the textile causes faster heating of the textile than is obtained with the case of hot platens, rollers, dies, or the like. Of course, a faster heating of the textile means that the time for setting the deformation is reduced.

With regard to the mechanism involved in the process of the invention, it is believed that during the heat treatment the MBA reacts with the wool, establishing crosslinks, for example, through free amino groups in the wool adding to the double bonds on either end of the MBA molecule. Such cross-linking can be illustrated by the following equation:

2Ker-NH2 (In the above formula Ker represents the polypeptide chain of the wool.) By this chemical reaction, the wool fibers are set in the position in which they are constrained during the heat-treating step. In addition to such crosslinking reaction it is believed that a part of the MBA polymerizes within the fiber during the heat-curing step and assists in attaining the desired result by resiliently maintaining the fibers in the predetermined configuration even after the mechanical forces holding the textile in constraint are removed. However, since durable arrangements are produced in wool fabrics by MBA in very small amount-far below the levels required to form pleats, creases, etc., with starches, resins, and similar conventional agentsand since MBA is effective in the absence of any polymerization catalyst it is believed that the mechanism primarily responsible for the effectiveness of the process of the invention is the reaction of MBA with the wool rather than a mere polymerization of MBA.

The sequence of the operations of (a) application of MBA and (b) mechanical deforming of the textile is not critical. Thus the textile may be treated with MBA, deformed to the desired pattern and heated while constrained in each pattern. On the other hand, the textile may be deformed to the desired pattern, the MBA applied, and the textile heated while constrained in such pattern.

In a preferred modification of the invention, the solution applied to the textile contains an alkaline agent in addition to MBA. The presence of the alkaline agent has been found to enhance the permanence of the textile arrangements produced by the invention. Various alkaline agents may be employed for this purpose, as for example, alkali metal bicarbonates, carbonates, tetraborates, phosphates, pyrophosphates, or other watersoluble salt which exhibits an alkaline buffering capacity. Usually, the amount of alkaline agent is regulated so that the solution has a pH of about 8 to 11.5. The aqueous solution of MBA, whether or not it contains an alkaline agent, may also contain a conventional wetting agent to assist in penetration of the solution into the structure of the textile. Suitable for this purpose are such agents as, for example,

soaps, long-chain alkyl sodium sulphates or sulphonates, long-chain alkyl benzene sodium sulphonates, esters of sulphosuccinic acid, etc., typical examples being sodium oleate, sodium lauryl sulphate, sodium dodecane sulphonate, sodium alkyl (C -C benzene sulphonates, sodium dioctylsulphosuccinate, etc. Agents of the non-ionic type may be used, for example, the reaction products of ethylene oxide with fatty acids, polyhydric alcohols, alkyl phenols and so forth. Typical of such agents are polyoxyethylene stearate, polyoxyethylene ethers of sorbitan monolaurate, isooctyl phenyl ether of polyethylene glycol, etc. Cationic agents may also be used as, for example, long-chain alkyl trimethyl ammonium chlorides, bromides, and methosulphates. Only a small amount of wetting agent is needed, i.e., about 0.05 to 0.5% by weight based on the weight of the solution.

In an alternative modification of the invention, the textile prior to application of MBA, is impregnated with an alkali metal bisulphite or sulphite. This technique has the advantage that the permanence of the creases, pleats, or other arrangements imparted to the textile is somewhat enhanced. In employing this modificaiton of the invention, the textile to be treated is first impregnated with an aqueous solution of alkali sulphite or bisulphite, the latter being preferred. Very dilute solutions of the sulphite or bisulphite are used, namely, those having a concentration of about 0.05 to 0.1%, to avoid any bleaching effect. Thus, it has been observed that with sodium bisulphite solutions of concentrations above 0.1%, there may be a bleaching of textiles dyed with certain conventional wool dyes. After application of the bisulphite or sulphite solution, the fabric may be dried in air before it is treated with the MBA solution. However, drying is not critical and the fabric wet with the sulphite or bisulphite solution may be directly treated with the MBA solution and further processed as above described. In applying this modification of the process of the invention the MBA solution may contain an oxidizing agent which forms a redox catalyst system with the previously-applied sulphite or bisulphite. As the oxidizing agent, one may use such agents as an alkali metal persulphate, hydrogen peroxide, benzoyl peroxide, acetyl peroxide, tertiary butyl peroxide, ascaridole, alkali metal peracetates, perbenzoates, etc.

In applying the modification of the invention wherein MBA is employed in connection with a bisulphite (or sulphite) and an oxidizing agent, a certain degree of polymerization of the MBA on the wool fibers will occur. Such result may be desired, particularly if the shrinkage characteristics of the wool are to be improved in addition to establishing a stable set of predetermined pattern. In a further extension of this phase of the invention, one may proceed by impregnating the wool textile with MBA plus any redox catalyst system, forming the textile into a predetermined pattern, and while constraining it in such pattern subjecting it to heat to cure it and set it in the predetermined pattern. Typical redox catalyst systems (combinations of oxidizing and reducing agents which produce free radicals) which are suitable for the purpose are disclosed in Patent No. 3,005,730 and any of these redox systems may be employed in an application of this aspect of the invention.

The process of the invention may be applied to wool textiles in the form of threads, fibers, yarns, slivers, rovings, woven fabrics, knitted fabrics, felts, or garments made of woven or knitted fabrics. The textiles may be white or dyed goods. Typical applications of the invention are: to provide garments with pleats, creases, or other arrangements customary in tailoring; to provide sheets of fabric with pre-formed pleats so that the product may be used for the fabrication of skirts, draperies, etc.; to produce crimp, twist, or other configuration in yarns, threads, and the like. Further applications of the invention will be obvious to those skilled in the art from the above illustrations.

As noted hereinabove the critical agent in accordance with the process of the invention is MBA. Although We have not extended our trials to related compounds, it would be expected that similar results could be attained by the use of closely-related homologues of MBA, as for example, N,N'-methylene bis-methacrylamide.

The invention is further demonstrated by the following illustrative examples:

EXAMPLE I (1) The fabric used in these runs was an all-wool, undyed, tropical worsted. Samples of this fabric were immersed in different liquids (as described below), then run through a padding roll to squeeze out excess liquid. Wet pick-up of liquid on the padded fabric was about 100%.

The liquids used were:

(A) Aqueous solution of MBA (1.12%).

(B) Aqueous solution of MBA (1.12%) and borax (C) Water (control).

(D) Aqueous solution of borax (0.5%) [control].

(2) The four samples of fabric were then each folded over to form a crease parallel to the warp direction of the fabric. The creased fabrics were then placed in a tailors steam press. There they were pressed for 2 minutes: one minute with direct application of steam, one minute with the steam turned off. Temperature reached by the fabric was about 140 C. The fabric samples were then removed from the press. It was observed that all the samples displayed sharp creases.

(3) To test the durability of the creases, the following test was applied to each sample.

Each sample Was immersed for 30 minutes in hot (75 C.) water containing 0.05% of a non-ionic wetting agent (Triton X-100, isooctylphenyl ether of polyethylene glycol). After this soaking, the samples were rinsed in water, then laid out fiat (with the crease opened out) on a table to air dry. After the samples were dried they were examined to determine the character of the crease. The creases were rated on the following scale:

6 to 7=excellent crease retention.

4 to 5=good crease retention.

2 to 3=fair crease retention.

0 to 1:.no crease to trace of crease retention.

The results are set forth below.

EmMPLE II The fabric used in these runs was the same as in Example I, namely, an all-wool, undyed, tropical worsted. Samples of this fabric were immersed in an aqueous solution of sodium bisulphite (0.1% then run through padding rolls to squeeze out excess liquid. Wet pick-up of the solution on the fabric was about 60%. One-half the samples were dried in warm air (120 F.), the remainder was left damp. Both lots were then treated as described below.

The fabric samples were immersed in different liquids (as described below), then run through pad rolls to squeeze out excess liquid. Wet pick-up of liquid on the samples was about 100%.

The liquids used were:

(A) Aqueous solution of MBA (1.12%) and borax 6 (B) Aqueous solution of MBA (1.12%), borax (0.5%)

and potassium persulphate (0.17%). (C) Water (control).

The samples of fabric were creased and heat cured as described in Example 1, part 2, and the creases tested as in Example I, part 3. The results are tabulated below.

The fabric used in these runs was an all-wool, undyed, tropical worsted.

One-half the lot of wool fabric was immersed in an aqueous solution of sodium bisulphite (0.1%), then run through pad rolls to remove excess liquid. Wet pick-up of the bisulphite solution on the fabric was about 60%. The other half of the lot was was not given any treatment.

The bisulphite-treated and the untreated fabric samples were then sprayed with aqueous solutions containing 0.5% borax and varying proportions (0.28% to 1.12%) of MBA. After application of these solutions the samples were creased and heat cured as described in Example I, part 2 and tested as described in Example I,

It is acknowledged that it is known in the art (Pardo and Lundgren, US. Patent 3,005,730, October 24, 1961) to utilize MBA for shrinkproofing wool textiles. This is accomplished by applying MBA to the textile and polymerizing it in situ in the presence of a redox catalyst system (typically a combination of a sulphite and a peroxide). This prior patent does not, however, disclose any process of setting textiles with MBA. Moreover, the fact that setting of textiles can be accomplished in accordance with the invention by employment of MBA in the absence of any redox catalyst or other polymerization catalyst indicates that the mechanism of MBA in establishing a stable set in wool textiles is completely distinct from its abiltiy to shrinkproof wool textiles when polymerized in situ thereon.

Having thus described the invention, what is claimed is:

A method for imparting a stable set to wool textile material which comprises distributing on a wool textile a solution containing solely water, N,N'-rnethylene bis- 2,933,409 4/60 Binkley et a1. 117-1l acrylamide, and a Water-soluble alkaline buffering agent, 2,957,746 10/60 Buck et a1 8-129 deforming the textile in a predetermined pattern, and ,97 2 3/61 WarnOCk et al. d- 38144 While constraining it in such pattern subjecting it to heat 3,005,730 10/61 Pardo et a1 117-141 to set it in the predetermined pattern. 5 OTHER REFERENCES References Cited by the Examine;- Frick et 211.: Textile Research Journal, Vol. 27, pp. 92-

99, 1957. UNITED STATES PATENTS 2,475,846 7/49 Lundberg 1o NORMAN G. TORCHIN, Primary Examinz'er. 2,769,584 11/56 Zinamon et a1 223-30 THOMAS HICKEY, Examiner. 

